Method of assembling electronic equipment

ABSTRACT

An electronic equipment cabinet is shown having an integrated cover panel which provides a plurality of connector receptacle positions to which outside equipment may be connected. Connector contacts are snap locked into the receptacle positions. The connector receptacle contacts are automatically bridged when the mating connector plug is removed to short circuit the connector contacts. L-shaped bridging contacts maintain positional stability while L-shaped connector contacts permit direct insertion of the contacts into a printed circuit board within the equipment cabinet. Two unitary ground strips are fashioned to provide shielding shrouds around each of the plurality oconnector receptacles while attaching as single units to the cover panel and closing ground contact with the cabinet housing. This cabinet arrangement finds one use as a trunk access unit to interconnect a plurality of data stations into a local area ring network.

This is a division of application Ser. No. 437,245, filed Nov. 16, 1989now U.S. Pat. No. 5,053,926 issued Oct. 01, 1991.

TECHNICAL FIELD

This invention relates to electrical connector assemblies and, moreparticularly, to electronic cabinet cover panels with integratedelectrical connector assemblies which are less costly to fabricate andassemble.

BACKGROUND OF THE INVENTION

Electronic equipment is often connected to other electronic equipment orto transmission facilities by means of multiconductor connectors. Suchconnectors are fabricated in mating pairs, one male and one female,which fit together to complete an electrical circuit between each of theconductors of one connector and the corresponding conductor of the otherconnector. For many applications, it is further necessary to provideelectromagnetic and/or electrostatic shielding around the conductors toprevent the unwanted leakage of electromagnetic energy. Due to thenecessity of providing all of these functions for a plurality ofconductors, the design of such connectors has been complicated andrequired the assembly of many different parts, thereby increasing thecost and complexity of such connector assemblies. In some applications,the design of multiconductor connectors is aggravated by the need toprovide a large number of such connectors in close proximity to eachother. One such application is in a central connection box for localarea data networks.

Many local area networks (LANs) have a ring architecture in which aplurality of stations are connected together in a ring. Messages arethen transmitted from one station to another around the ring, usingaddress information in the message header to deliver the messages to theproper destination. In such local area networks, such as within a singlebuilding, it is convenient to interconnect stations in a star network,with a central connection point, and with stations connected to such acentral point by way of trunk transmission lines. In order to realize aring network with a star architecture, it is necessary to route both anoutgoing and an incoming trunk line between each station and the centralpoint. At the central point, the trunk line terminations areinterconnected into a serial ring. The various timing, framing andcontrol circuits for enabling ring transmissions are also located at thecentral location. Finally, the central connection point is arranged toensure ring transmission continuity in the absence of one or morestations from the star network. Such a central interconnection circuitis commonly known as a trunk access unit (TAU).

It will be noted that a trunk access unit includes many parts, bothelectronic and mechanical. The mechanical parts, and, in particular, theconnectors which are used to connect the stations to the network mustprovide connections for the two trunk lines (four conductors) going toeach station. Moreover, these connectors must provide bridging contactswhich automatically connect the outgoing trunk line contacts to theincoming trunk line contacts when the station connector is unpluggedfrom the TAU unit. connections must also be provided from the trunk lineterminations to central control circuitry, preferable mounted on aprinted circuit board (PCB) mounted in the TAU. Due to the high datarate normally used in such networks, the connector contacts must beshielded to prevent interference from signals leaking from the differenttrunk lines terminating in the TAU. As might be expected, these manyfunctions are accommodated by connector structures and shieldingstructures which must be assembled in very particular relationships. Inthe prior art, these complicated structural relationships have beenaccommodated by painstaking assemblies of many small parts intosubassemblies which, in turn are assembled into the final TAU assembly.

Electromagnetic shielding, for example, has been provided in the priorart by individual conductive shrouds assembled to surround each set ofconnector contacts and electrically mating with similar shieldingshrouds forming part of the mating connector. These shrouds weretypically assembled from piece parts mounted around each set ofcontacts, using fastening devices such as screws or rivets, a costly andtime-consuming operation.

The connectors themselves typically comprise several non-conductivehousing pieces into which are assembled the contact pins and aroundwhich the shielding shrouds are secured. Finally, all of the shieldedconnector assemblies are assembled into a cover panel closing one faceof an electronics cabinet. It can thus be seen that the fabrication ofshielded connectors for access to electronic equipment cabinets involvesthe assembly of large numbers of parts involving many separatesubassembly steps, thereby increasing the cost and reducing thereliability of the resulting assemblage. Lower cost and more reliableelectronic equipment cabinets (such as TAUs) would result from reducingthe number of parts required to be assembled in order to provide suchequipment cabinets.

SUMMARY OF THE INVENTION

In accordance with the illustrative embodiment of the present invention,a simple and reliable electronics equipment cabinet construction isprovided for terminating multiple conductor connectors. Rather thanfollowing the usual construction technique of providing a plurality ofaccess holes in a metallic chassis, one for each of the individualconnectors, one entire face of the chassis is left open and anon-conductive, molded cover panel is used to close the open face of thechassis. Molded directly into the cover panel are the mounting supportsfor a plurality of snap-in connector contact pins as well as a mountingsurface for metallic shielding shrouds surrounding the contact pins andcompleting the ground shield to the chassis housing. Finally, one end ofeach contact pin is formed and oriented for direct insertion into asoldering hole in a printed wiring board (PWB), thereby avoiding thenecessity of soldering individual wires from the contact pins to thePWB.

In the event that a plurality of connector plugs must be terminated inthe same equipment cabinet, as is required for the Trunk Access Unit(TAU) of a Local Area Network (LAN) with a ring architecture, all of theconnector contact pin mountings for all of the connectors are moldedinto the same cover panel. Moreover, the shielding shrouds for all ofthe connector conductors are fabricated by using one or two conductivestrips, progressively stamped to form a plurality of shrouds, one foreach of the plurality of connectors, yet comprising only one or twopiece parts requiring separate assembly steps.

In the case of a trunk access unit for a local area ring network, forexample, a multiple connector box must provide a plurality of shieldedreceptacles for connection to each of a plurality of trunk lineterminating plugs. In order to provide shielding for all of the contactsin all of the connector receptacles of the TAU, two continuousconductive ground strips are fabricated to provide a separate shieldingshroud around each set of contacts and yet comprise a single, continuousground plane which can be placed, as a unit, in contact with theconductive housing or chassis around the printed circuit board.Continuous shielding around all of the data line contact pins is therebymaintained with only a pair of ground plane strips, thereby reducing thecost and complexity of the TAU assembly. For ease in assembly, theseground strips are attached to the interior of a integral,non-conductive, molded cover plate for the TAU circuit box such thatindividual four-sided shrouds are formed for each connector position.

In further accord with the illustrative embodiment of the presentinvention, the single molded cover panel also provides a plurality ofconnector receptacle positions each adapted to receive onemulti-conductor connector plug from outside equipment. Each receptaclecontact pin is designed to be snap locked over shoulders molded intogrooves in teh interior of the cover panel. Together, these contactsform a connector receptacle assembly for contacting the pins of a matingconnector plug. The other end of each contact pin is formed and orientedfor direct insertion into a soldering hole in a printed wiring boardwithin the electronic cabinet.

In accordance with one feature of the present invention, the connectorend of the contact pin is bent back on itself to provide contactsurfaces at the free end having elastic freedom of movement in the planeof the contact pin. This free end is formed into a ramp-shaped brushingcontact surface which makes contact with a mating ramp-shaped brushingcontact surface on a connector pin in a mating connector plug. The freeend of the contact pin also has a flat contact surface which is normallyurged into engagement with a bridging contact. That is, when the matingconnector contact pin is in engagement with the receptacle contact pin,the brushing contact on the ramp portion of the receptacle pin depressesthe flat surface away from the bridging contact, breaking the bridgingcircuit. When the mating connector plug is removed from the receptacle,however, the flat surface of the receptacle contact pin, under theinfluence of the spring elasticity, is allowed to return to the bridgingcontact and thereby close the bridging circuit.

In accordance with yet another feature of the present invention, inorder to insure positional stability of the bridging contacts, and hencereliable bridging action, bridging contact strips are formed withshoulders parallel to the contact surface and locked into the moldedcover panel at right angles to the direction of motion of the receptaclecontact pins. In this way, the contact pressure does not tend todislodge the bridging contact or change the contact spacing and a highdegree of dimensional stability is maintained.

In summary, the interior of the molded cover plate serves as a mountingsurface for both the receptacle connector contact pins, for the bridgingcontact strips and for the shielding shrouds. Once the receptacleconnector contact pins, the bridging contact strips, and ground stripsare mounted in the cover plate, the free ends of the connector contactpins can be soldered directly to the printed circuit board. The entireassembly of cover plate, contacts, grounding strips and printed circuitboard can then be mounted in the electronic box with the cover platecovering the remaining open side of the circuit box and providing aplurality of shielded female connector receptacles for mating withshielded male connector plugs.

One of the major advantages of a trunk access unit in accordance withthe present invention is the formation of shielding shrouds for aplurality of connector receptacles with only two grounding strips whichcan be pre-assembled to the cover plate to significantly reduce assemblytime and cost. Another advantage of the present invention is the abilityto directly solder the receptacle connector contact pins to the printedcircuit board, thereby avoiding the need for interconnecting leads.Finally, the forming of the bridging contact strips with shouldersparallel to the contact surface substantially reduces the positionalinstabilities of the bridging contacts. Such instabilities can result inpoor electrical contact or no contact at all, thereby rendering theentire ring network unusable.

Most importantly, however, is the ability to provide one or moremulticonductor shielded connectors for an electronic equipment cabinetby molding the support structures for contact pins, shielding shroudsand, if necessary, bridging contacts, all in the same integral coverpanel which closes a single open face in the equipment cabinet. Thenumber and complexity of the assembly steps necessary to fabricateequipment cabinets in accordance with the present invention issignificantly less than those required in the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS

A complete understanding of the present invention may be gained byconsidering the following detailed description in conjunction with theaccompanying drawings, in which:

FIG. 1 shows a simplified circuit diagram of a ring data network inwhich the improved multiple access equipment cabinet according to thepresent invention may be used;

FIG. 2 shows an exploded perspective view of a portion of an electronicequipment cabinet such as a trunk access unit cabinet in accordance withthe present invention showing portions of the grounding strips and coverpanel assembly;

FIG. 3 shows a partial exploded perspective view of the contact assemblyin the connector receptacle portion of the cover panel of FIG. 2,showing the contact arrangement and assembly in accordance with thepresent invention;

FIG. 4 shows a partial cross-sectional view of the assembled electroniccabinet showing the connector receptacle portion of the cover panel ofFIG. 2; and

FIG. 5 shows a rear elevational view of one of a portion of theassembled electronic cabinet of FIGS. 2, 3 and 4.

To facilitate reader understanding, identical reference numerals areused to designate elements common to the figures.

DETAILED DESCRIPTION

Before proceeding to a detailed description of the present invention, atypical application will be described in which a plurality ofmulticonductor connectors terminate in a single electronic cabinet.Referring more specifically to FIG. 1, there is shown a general blockdiagram of a local area ring network comprising two trunk access units(TAUs) 10 and 11 each providing a plurality 12 and 13, respectively, ofconnector receptacle positions. A plurality of data station units 14-15are connected to trunk access unit 10 by way of transmission lines16-17, terminated in male connector plugs each mating with one of theconnector receptacle positions 12 of TAU 10. Similarly, a secondplurality of data station units 18-19 are connected to trunk access unit11 by way of transmission lines 20-21, terminating in male connectorplugs each mating with one of the connector receptacle positions of TAU11.

TAU 10 and TAU 11 each comprise a multiconductor, multiconnectorelectronic cabinet which are interconnected together to form a ring byway of transmission lines 22 and 23, each connected between connectorreceptacles at one end of TAU 10 and one end of TAU 11. TAUs 10 and 11include electronic circuitry, preferable mounted on a printed circuitboard, which, among other things, interconnects the multiplicity ofconnector positions in series to maintain the ring architecture. To thisend, each of transmission lines 16-17 and 20-21 actually comprise twotransmission lines, one outgoing transmission line to the associatedstation unit and one incoming transmission line back from the associatedstation unit.

In accordance with common practice, the connector receptacle positionson TAUs 10 and 11 are arranged to bridge the incoming and outgoingtransmission lines when the male connector plug is removed from theconnector receptacle position, thus maintaining the ring architectureregardless of how many of the connector positions are unoccupied. Trunkconnector plugs suitable for mating with the connector receptacles 12and 13 of TAUs 10 and 11 are the four position data connectors coded IBMP/N4760554, available from the International Business MachinesCorporation, or AMP P/N 554922-1, available from AMP, Incorporated.

In many applications, the local area ring network of FIG. 1 is locatedin a geographically local area such as a single building or closelyspaced buildings such as on a college campus. In that case, thetransmission lines 16-17, 20-21, 22 and 23 can be simple twistedtelephone pairs. TAUs 10 and 11 are preferably located in equipmentclosets so that all of the wiring can be brought to one or more centrallocations. It is, of course, obvious that the data ring network can bemore dispersed geographically and the transmission lines made up ofcoaxial cables, optical fibers or other suitable transmission media. Inany case, the electronic equipment within TAUs 10 and 11 suitablyprepare data signals for launching on and reception from thetransmission lines actually used.

While only two trunk access units are shown in FIG. 1 for illustrativepurposes, it is clear that only one need be used, or a plurality greaterthan two can be used, depending on the number of station units to beinterconnected. As shown in FIG. 1, a fixed number of station units canbe accommodated with a single TAU (eight in FIG. 1, reserving two forinter-TAU connections). In any event, the cost of such ring networks isheavily influenced by the cost of fabricating and assembling trunkaccess units such as units 10 and 11. The present invention comprisesimproved mechanical arrangements for multiple access electroniccabinets, such as trunk access units 10 and 11, which can fabricated andassembled more quickly and less expensively than prior art cabinets.

Referring more particularly to FIG. 2, there is shown a partial explodedview of the TAU 10 or 11 of FIG. 1 comprising a conductive five-sidedcontainer box or cabinet 30 for containing and shielding all of theelectronic and mechanical parts of the TAU. A non-conductive, moldedcover plate 31 is mounted over the open end of cabinet 30 by a pluralityof self-tapping assembly screws such a screw 32. Cover plate 31 has aplurality (ten in FIG. 2) of female connector receptacle positions 33molded therein to receive, from the rear, contacts connected toelectrical circuitry within cabinet 30 and to receive, from the front, amating connector plug from a remote station unit such as units 14 . . .15 and 18 . . . 19 of FIG. 1. Adjacent to each of cowlings 33 is anopening 34 through which a light emitting diode (LED) can be viewed fromthe front to determine if the corresponding TAU circuit is operative.

An upper ground strip 35 and a lower ground strip 36 are provided withholes 37 and 38, respectively, for attaching the ground strips 35 and 36to the interior of front panel 31. Extensions 39 and 40 of upper groundstrip 35 are positioned directly above the pairs of conductors formingthe incoming and outgoing trunk lines, respectively, when the TAU unitis assembled, while extensions 41 and 42 of lower ground strip 36 arepositioned directly below the pairs of conductors. Together withvertical extensions 43 and 44, extensions 39-42 form a four-sided shroudsurrounding the conductors of the connector receptacle to be describedbelow. Moreover, these conductive shrouds mate with correspondingshrouds in the mating plugs, thus insuring continuous shielding for theenclosed conductors. Upper ground springs 45 and lower ground springs 46serve to electrically connect ground strips 35 and 36, respectively, atregular spaced intervals, to the interior of cabinet 30, therebyinsuring an adequate ground connection. Vertical tabs 47 on lower groundstrip 36 fit between extension 43 and the adjacent extension 44 tocomplete the ground shield across the open face of cabinet 30.

It will be noted that ground shrouds for a large plurality of connectorreceptacles are formed with only two grounding strips 35 and 36. Indeed,a single progressively stamped ground strip could be used in place ofground strips 35 and 36, but with a slight increase in assemblydifficulty. In the preferred embodiment shown in the figures, a twopiece grounding strip is used for convenience. This is in contrast toprior art grounding shrouds formed of at least two grounding strips foreach receptacle, and requiring separate assembly around each receptacle.The multiple receptacle grounding shrouds of the present inventionprovide a distinct advantage in ease of assembly.

The details of the receptacle contacts can be better seen in FIG. 3which is an exploded partial view of the cover panel 31 of FIG. 2 viewedfrom the rear so as to reveal the contact details. Each receptacleincludes four line contact pins 50, 51, 52 and 53 for making contact atone end to mating contact pins on a connector plug (not shown) and formaking contact at the other end to a printed wiring board 54 havingprinted circuit wiring 55. The contacts 50-53 are each L-shaped with atongue 56 (best shown in FIG. 4) at one end for insertion in printedwiring board 54 and being bent back on themselves at the other end toform resilient spring contacts having a ramplike wiping contact portion57 which makes brushing contact with similar wiping contacts on theconnector plug, and a flat tail portion 69 to make contact with bridgecontact elements to be described below. Connector pins 50-53 areassembled to cover panel 31 by pushing them into grooves 58. To thisend, a wider central portion of each of contacts 50-53 is dimensioned tofit snugly into slot 58 while the two end portions of contacts 50-53 arenarrower, dimensioned to fit through slots 90 above slots 58. The bottomof slot 58 has a shoulder 92 molded therein (FIG. 4) over which detents59, and matching detents 91 are snapped to lock the connector contacts50-53 into position. As also can be better seen in FIG. 4, the tabs 60on lower ground strip 36 serve to properly position printed wiring board54 when the parts are assembled.

It will be noted that contact pins 50-53 are L-shaped to facilitatedirect connection of the contact pins into the printed wiring board 54.Such direct connection to the printed wiring board, in contrast to theprior art technique of running wires from the ends of the contact pinsto the printed wiring board, greatly simplifies the assembly of the TAU.

An upper front bridging contact 61 has horizontal shoulders 93 which fitinto horizontal grooves 62 in cover panel 31 while a lower rear bridgingcontact 63 has similar horizontal shoulders 94 which fit into horizontalgrooves 64 in cover panel 31. When assembled, bridging contact 61interconnects tail portions 69 of contacts 51 and 53 while bridgingcontact 63 interconnects tail portions 69 of contacts 50 and 52. Cutouts65 and 66 in front bridge 61 prevent bridge 61 from engaging contacts 50and 52 while cutouts 67 and 68 in rear bridge 63 prevent bridge 63 fromengaging contacts 51 and 53.

It will be noted that the bridging contacts 61 and 63 are assembled intocover panel 31 by insertion of shoulders 93 and 94 into slots 62 and 64,respectively, which are at right angles to the direction in whichcontact pins 50-53 exert pressure on the bridging contacts. In contrastto prior bridging contacts, fabricated as planar plates, such contactpressure is unable to dislodge or move the bridging contacts 62 and 64,and thereby interfere with secure electrical connection.

In FIG. 4 there is shown a partial cross-sectional view of the assembledTAU through a typical connector receptacle position. The cabinet 30 isseen to engage the ground springs 45 and 46 to complete the electricalshield. The cabinet 30 fits into grooves 70 and 71 in the rear of coverpanel 31. Cylindrical studs 72 fit through holes 37 and 38 in upperground strip 35 and lower ground strip 36, respectively. These groundstrips can then be attached to the rear interior of cover panel 31 byheat staking, i.e., partially melting the studs 72 to form a globs 73 ofplastic material larger than the holes 37 and 38 and hence holding theground strips 35 and 36 tightly to the cover panel 31. An upper pluglocking clip 74 and a lower plug locking clip 75 serve to retain themating connector plug in the receptacle once it is inserted. The detailsof locking clips 74 and 75 form no part of the present invention andwill not be further described here. These locking clips are, of course,designed to mate with the aforementioned IBM P/N4760554 and AMPP/N554922-1 plugs.

The perpendicular tabs 95 of upper grounding strip 35 fit into locationboss 76 in the interior of cover panel 31 for positional stability whilecorresponding perpendicular tabs at the bottom of lower grounding strip36 fit into location boss 77 for the same purpose. As can be best seenin FIG. 4, the extensions 39-40 of upper grounding strip 35 and theextensions 41-42 of lower grounding strip 36 completely encircle thecontacts 50-53 through to the front side of cover panel 31, while theside extensions 43 and 44 (FIG. 5) complete the shielding shroud.

In FIG. 5 there is shown a partial rear elevation view of one of theconnector receptacles of the present invention showing the assembledtrunk access unit. The tongues 56 are soldered into printed wiring board54 while the upper and lower ground strips 35 and 36 are attached tocover panel 31 by melted studs 73.

In FIG. 6 there is shown a partial front elevation of the cover panel 31showing the details of the connector pin slots 58 separated by insulatedlands 80 and 81. Grooves 84 at the front end of the connector pin slots58 form the front end of shoulders 92 and receive the mating detent onthe underside of connector pins 50-53, as best shown in FIG. 4. Upperlocking clip 74 and lower locking clip 75 have not been shown in detailsince they form no part of the present invention. Grooves 82 and 83receive extensions 39 and 40 of upper ground strip 37.

The trunk access unit (TAU) is assembled as follows. First, the frontbridge 61 is pressed into slots 62 or cover panel 31. Then the rearbridge 63 is pressed into slots 64 of cover panel 31. Next, all of thecontact pins corresponding to contact pins 50-53 are soldered intoprinted wiring board 54 to form a first subassembly. The upper groundstrip 35 and the lower ground strip 36 are then heat stamped to the rearof the cover panel 31 to form a second sub-assembly. The first andsecond subassemblies are then assembled to each other by pressing thecontact corresponding to pins 50-53 into the slots 58, snapping thedetents 59 into place, thereby forming a cover panel assembly. Finally,the entire panel cover assembly is assembled to cabinet 30 by insertingthe printed wiring board 54 into the cabinet 30 and the cover panelassembly attached on the open face of cabinet 30 by means of screws 32.It is obvious that this procedure involves far fewer steps and is muchless costly than prior art procedures requiring separate shrouds to beassembled for each connector receptacle and requiring individualelectrical connections to be wired from each of the contact pins to theprinted wiring board. Moreover, in the prior art, the cover panel itselfhad to be fabricated in several parts to permit the insertion of thebridging contacts.

While the illustrative embodiment of the present invention includes aplurality of integrally molded connector receptacles, it is obvious thatonly one such connector receptacle need be provided. Such a singlereceptacle embodiment would be used, for example, to provide a wallreceptacle for connecting an electronic device to concealed wiringwithin the walls of a building.

It should also be clear to those skilled in the art that furtherembodiments of the present invention may be made by those skilled in theart without departing from the teachings of the present invention.

What is claimed is:
 1. A method for assembling electronic equipmentcomprising the steps ofmolding a cover panel having at least onereceptacle position molded therein, each said position includingshoulders for snap locking separate connector contacts onto saidposition, soldering one end of a plurality of said connector contacts toa printed circuit board, and snap locking said connector contacts ontosaid shoulders in said cover panel to form a connector assembly integralwith said cover panel.
 2. The method according to claim 1 furthercomprising the step offastening no more than two progressively stampedground strips to the interior of said cover panel to form shieldingshrouds around said connector contacts.
 3. The method according to claim1 further comprising the step ofinserting at least one bridging contactinto said cover panel to engage at least two of said connector contacts,said bridging contacts being held in said cover panel by shoulders atright angles to the direction of movement of said connector contacts. 4.The method according to claim 2 further comprising the step ofattachingsaid cover panel to an electronic equipment cabinet so as to engage saidground strips with the interior surface of said cabinet.